Controlled Drug Delivery Studies of Biological Macromolecules: Sodium Alginate and Lignosulphonic Acid Films S. Giridhar Reddy, Akanksha Saxena Pandit Chemistry Department, Amrita School of Engineering, Amrita Vishwa Vidyapeetham, Bengaluru Campus, Bangalore 560035, Karnataka, India Correspondence to: A. S. Pandit (E - mail: s_akanksha@rediffmail.com or s_akanksha@blr.amrita.edu) ABSTRACT: The ciprofloxacin (CPX)-loaded blends made of sodium alginate and lignosulfonic acid (LS) were prepared by solution casting method in the ratio of 80/20. The blends were crosslinked for different intervals of time to control the drug release. The drug release was investigated for 24 hours in different pH medium (1, 4, 7, and 9). It was confirmed that drug release is controlled by dif- fusion through the polymer matrix followed by the erosion of the polymer. The pH of the surrounding medium influences the drug solubility, swelling, and degradation rate of the polymer and therefore the overall drug release process. The blend shows minimal drug release at pH 1 and 9, whereas moderate release at pH 4, but rapid release at pH 7. Further FTIR, XRD, and SEM characteriza- tion are carried, to confirm the chemical-interaction, crystallization effects, and compatibility between the blend matrixes. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40442. KEYWORDS: biodegradable; biocompatibility; blends; drug delivery systems Received 15 October 2013; accepted 15 January 2014 DOI: 10.1002/app.40442 INTRODUCTION There are steady efforts from decades to release the drug in a controlled manner from biological macromolecules. In most cases, the purpose is to make a product that maintains a pro- longed therapeutic effect at a reduced dosing frequency. It is important to supply drugs to the patient in a controlled manner enabling the optimum concentration of drugs and prolonged effectiveness. Crosslinked blend films have been investigated as controlled drug delivery systems, taking advantage of their func- tion to release drugs. 1–3 The drugs confined in a polymer net- work are released in a controlled rate by the swelling behavior of blend film, the pore size of a polymer network, the affinity between drugs and polymer and their degradation with various pH medium in vivo. 4–11 In the last decade, medical and phar- maceutical industries are showing an increased interest, espe- cially in biological macromolecules and alginates in particular. These materials have found numerous applications in pharma- ceutical sciences due to their usefulness in specific applications as it enhances efficient treatment of esophageal reflux, creates multiquality calcium fibers for dermatology and wound healing. 12–17 It is also used for high and low-gel strength dental impression materials. Besides this, it naturally degradable, tablet binder and offers an attractive alternative for sustained-release systems. Sodium alginate (SA) is a freely natural available Bio- degradable polymer; it is non-toxic, biocompatible and offers advantages over synthetic polymers as it form hydrogels in aqueous medium. 18–24 All these advantages make alginates very useful material for biomedical applications. It was reported that, the drugs can be incorporated either as dissolved or dispersed phase into the polymeric matrix, which degrades in contact with the biological fluids, which allows a progressive release of the drug content. 25–27 But water solubility and mechanical weakness of SA membrane has been a drawback in its possible use for drug delivery applications. To improve the mechanical stability of membrane, SA needs to be blended with other poly- mer such as lignosulfonic acid (LS). LS is a natural biodegrad- able polymer, a plant byproduct formed from sulfite cooking of wood and is large tonnage wastes from pulp and paper industry which is well known, as super plasticizer. In this study, we prepared SA/LS blend films. To investigate these films in several controlled release applications, it was nec- essary to have an overall understanding of their properties. We used ciprofloxacin (CPX) as a model drug, to study the influ- ence of drug release from SA/LS films as function of pH of the release medium and the crosslinking time with calcium chloride solution etc. We wish this film can lead to a successful applica- tion for localized drug delivery in vivo or in vitro environment. Further, the drug loaded blends are subjected for FTIR charac- terization, XRD, and SEM to test the compatibility between the polymer matrixes and drug. V C 2014 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2014, DOI: 10.1002/APP.40442 40442 (1 of 6)